Self-inflating inner tube for tires



P 1940. A. c1 SMITH 2,214,597

SELF-INFLATING INNER TUBE FOR T I RE S Filed May 24, 1939 1 5- J -5. V I29 INVENTOR ATTORNEY Patented Sept. 10, 1940 UNITED STATES enrsu'r cries5 Claims.

This invention relates to new and useful improvements in a pneumatictire and has specific reference to a self-inflating inner tube.

The invention proposes an inner tube which is characterized by asectional connecting rod mounted across the outer and inner Walls of theinner tube and associated with'an airpumping mechanism in "a novelmanner to continuously supply air to the inner tube under certainconditions while a vehicle is traveling which is equipped with the innertube. 1

More specifically, the invention proposes an arrangement whereby theflexing of the tire shoe and the inner tube during the turning of awheel of a vehicle provided with the same, causes the pumping of airinto the inner tube to maintain a predetermined pressure. Still furtherthe invention proposes an arrangement whereby the pumping actionsceasewhen the correct pressure is reached within 'the tire, irrespectiveof the fact that the wheel still continues to'turn and the tire portionsto flex.

Still further the invention proposes a novel arrangement by which it ispossible to adjust the relative positions of thesectionsof theconnecting rod previously mentioned to compensate for wear of thedevice.

Another object resides in constructing the connecting rod of rubberhaving suflicient stiffness to transmit the pumping action desired andyet be suificicntly flexible to bend and fold up in the event that thetire goes iiat.

For further comprehension of the invention, I

and of the objects-and advantages thereof, reference will be had-tothefollowing description accompanyingdrawing, and to the appended claims inwhich the various novel features of the invention are more particularlyset forth.

In the accompanying drawing forming a material part of this disclosure:

ii is a transverse sectional view of a tire and inner tube equipped witha self-inflating device constructed according to this invention.

Fig. 2 is a fragmentary enlarged view similar to a portion of Fig. 1 butshowing additional parts in section.

Fig. 3 is a horizontal sectional view taken on the line 3-3 of Fig. 2.

Fig. i is a horizontal'sectional view taken on the line fi4 of Fig.

Fig. 5 is a horizontal sectional view taken on the line 55 of Fig. 2.

Fig. 6 is a bottom view of the nutused for securing the pumping device.to the inner tube.

Fig. '7 is-afragmentarysectional view similar to the lower portion ofFig. 2 but illustrating a modified construction.

' The self-inflating inner tube, according to this invention, includesan inner tube casing l engageable into a tire casing H for mounting on awheel rim I2 in the conventional manner. A connecting rod extendsbetween walls of the casing and consists of an outer section It mountedwithin the casing It at a certain point on the ,outer wall of thecasing. This outer section 44 of the connecting rod is constructed ofrubber and is vulcanized on to the inner tube H) to be integraltherewith. The section it is provided with a head portion M disposedoutside of the. inner tube in engagement with the outer face thereof andthe shank portion M which extends into the inner tube. This connectingrod section I4 is of stiff rubber strong enough to transmit a force forflexing a bellows downwards as hereinafter more fully described, and 0fsufiicient flexibility to bend or double up in the event of a flat or"blowout without injury to the inner tube.

The connecting rod further consists of an inner'section having a reducedouter end lfi engaging into a receiving opening formed in the end Moithe outer section of connecting rod. This inner'section of connectingrod i is mounted within the tube casing ii! at a point opposed to thepoint on the outer wall where the outer section of connecting rod I4 ismounted. The inner endof the inner section of connecting rod I5 isformed with a bellows construction l5. This bellows construction isreinforced with imbedded cards It or similar reinforcement to preventlateral expansion thereof. The inner section of connecting rod I5 is"also'made'of rubbersuificiently rigid to transmit a compression forceto the bellows it and yet sufficiently flexible to bend or double up inthe event of a fiat or blowout without injury to the inner tube casing.

A resilient means is provided for normally urging the bellows l5 into anextended condition. This resilient means, essentially, consists of anexpansion spring l'i disposed within the bellows and acting between theinner and outer ends thereof. A tubular member 13 is mounted through theinner tube casing ill and the inner end of the bellows l5. This tubularmember l8 has an enlarged head Hi at its outer end within the bellows 15for gripping and engaging the material around the tubular member. A nutl9 threadedly engages on the outer end of the tubular member and againstthe outer face of the material of the inner tube casing ill for clampingthe bellows fixedly'in position under sufficient ill Gil

- and 26, into the inner tube.

pressure to make an air-tight connection so that the inner tube casingdoes not leak.

A check valve 20 for permitting air to enter the bellows through thetubular member I8 is mounted within the tubular member. This check valveis held within the end cavity 2! of the tubular member ill by aperforated cage 22. The arrangement is such that when air tends to enterthe bellows through the tubular member [8 the valve lifts, but isrestrained from moving too far by the cage 22. When air attempts toleave the bellows the valve 28 is forced upon its seat preventing thepassage of the air.

The outer end of the bellows l5 connects with a passage 23 extendingaxially through the inner section of connecting rod [5 and terminatingin a side opening 2 5 discharging into the interior of the inner tubecasing. Within this passage 23 there is a metal tube 25. This metal tubeis firmly anchored in position by intimately engaging the wall of thepassage. A conventional one way air valve 26 is mounted within. the tube25, and its threaded portion 26 threadedly engages the inner end of thetube 25.

The inner tube casing I0 is provided with a conventional valve stem 21passing through an opening 28 formed in the wheel rim l2. This stem 2'!is provided with a cap 29 and with an interior air valve, not shown onthe drawing, but generally used in conjunction with inner tubes. A bleedpassage 38 is formed longitudinally along one side of the stem 27 andcommunicates with a space 3! surrounding the nut 9. The nut I9 is formedwith a plurality of passages 32 connecting with the passage 3! to permitair .to enter the tubular member l8.

The operation of the device is as follows:

The inner tube casing in is inflated within the tire casing H in theconventional manner through the valve stem 21. The tire is brought up tothe pressure recommended by the manufacturer.- The parts are so designedthat during operation of a vehicle provided with the tire there will bea pumping action upon the bellows iii in the event that the pressure ofthe tire falls below the pressure recommended by the manufacturer.

It is known that, the portion of the tire engaging the ground iscaused'to flex inwards and as that particular portion moves away fromthe ground it flexes outwards. This flexing action is depended upon tocause the outer connecting rod section M to press inwards the innerconnecting rod section H?) which compresses the bellows l5. Theinterengagement of the adjacent ends of the connecting rods M and I5 isin the manner of a glove, that is, it may be pulled apart. They are notsecured together by glue or vulcanization or other holding medium. It isfor this reason that when a predetermined pressure within the tire isreached the outer section of the connecting rod [4 will be slightly ofithe adjacent end of the inner section of the connecting rod 55 and sothere will be no transmission of a compressing action on the bellows.

As the bellows i5 are compressed by the action of the connecting rod andare expanded by the action of the spring l'l, air will be pumped by thebellows in conjunction with the valves 20 This pumping action serves tomaintain the pressure within the tire except if there is a blowout or aleak that is too large to be made up by the operation of the pumpingsystem.

In Fig. 7 a modified form of the invention has been disclosed whichdistinguishes from the prior form in the fact that a nut l9 threadedlyengages the tubular member [8 forholding the tubular member in positionupon the wall of the inner tube casing I0. An auxiliary nut I9" isthreadedly engaged on the tubular member 18' and is adapted to bescrewed in or screwed out a small distance to hold the connecting rodsection [5 spaced at a predetermined distance from the wall of the rimI2. A set screw 33 serves tov fixedly secure the nut l9" to the tubularmember l8. The nut I9" is provided with the air passages 32 previouslyreferred to so that air from r understood that I do not limit myself tothe pre.

cise constructions herein disclosed and the right is reserved to allchanges and modifications coming within the scope of the invention asdefined in the appended claims.

Having thus described my invention, what I claim as new, and desire tosecure by United States Letters Patent is:

1. In an inner tube casing, a self-inflating means, comprising an outersection of connecting rod mounted within the casing at one point on theouter wall thereof, an inner section of connecting rod mounted withinthe casing at a point opposed to said point and on the inner wallthereof and at its inner end having a bellows area, resilient means forextending said bellows, a tubular member mounted through said casing andbellows, valves for directing air from said bellows to the interior ofsaid inner tube casing, said tubular member having a head upon its innerend and a nut threadedly engaged on its outer end, said-nut being formedwith grooves for the passage of air, said inner tube having a valve stemformed with a groove for the passage of air to the passages of said nut.

2. In an inner tube casing, a self-inflating means, comprising an outersection of connecting rod mounted within the casing at one point on theouter wall thereof, an inner section of.

connecting rod mounted within the casing at a point opposed to saidpoint and on the inner wall thereof and at its inner end having abellows area, resilient means for extending said bellows, a tubularmember mounted through said casing and bellows, valves for directing airfrom said bellows to the interior of said inner tube casing, saidtubular member having a head upon its inner end and a nut threadedlyengaged on its outer end, said nut being formed with grooves for thepassage of air, said inner tube having a valve stem formed with a groovefor the passage of air to the passages of said nut, and the valve stemof said inner tube extending through the rim of a wheel for the tire.

3. In an inner tube casing, a self-inflating means, comprising an outersection of connecting rod mounted within the casing at one point on theouter wall thereof, an inner section of connecting rod mounted withinthe casing at a point opposedto said point and on the inner wall thereofand at its inner end having a bellows area, resilient means forextending said bellows, a tubular member mounted through said casing andbellows, a check valve for permitting air to enter the bellows throughsaid tubular memher, a check valve for controlling a passage from saidbellows to the interior of said casing to permit air from the bellows toenter said casing, said inner and outer sections of said connecting rodhaving their adjacent ends connected together to operate said bellows ina slightly deflated condition of said tube, and means for holding saidinner section of the connecting rod at various relative positions to theouter section thereof to compensate for the wearing action of theengaged ends of said sections.

4. In an inner tube casing, a self-inflating means, comprising an outersection of connecting rod mounted within the casing at one point on theouter wall thereof, an inner section of connecting rod mounted withinthe casing at a point opposed to said point and on the inner wallthereof and at its inner end having a bellows area, resilient means forextending said bellows, a tubular member mounted through said casing andbellows, a check valve for permitting air to enter the bellows throughsaid tubular, member, a check valve for controlling a passage from saidbellows to the interior of said casing to permit air from the bellows toenter said casing, said inner and outer sections of said connecting rodhaving their adjacent ends connected together to operate said 'bellowsin a slightly deflated condition of said tube, and means for holdingsaid inner section of the connecting rod at various relative positionsto the outer section thereof to compensate for the wearing action of theengaged ends of said sections, including a nut threadedly engaged onsaid tubular member and adapted to abut the rim of a wheel equipped withthe tire.

5. In an inner tube casing, a self-inflating means, comprising an outersection of connecting rod mounted within the casing at one point on theouter wall thereof, an inner section of connecting rod mounted withinthe casing at a point opposed to said point and on the inner wallthereof and at its inner end having a bellows area, resilient means forextending said bellows, a tubular member mounted through said casing andbellows, a check valve for permitting air to enter the bellows throughsaid tubular member, a check valve for controlling a passage from saidbellows to the interior of said casing to permit air from the bellows toenter said casing, said inner and outer sections of said connecting rodhaving their adjacent ends connected together to operate said bellows ina slightly deflated condition of said tube, and means for holding saidinner section of the connecting rod at various relative positions to theouter section thereof to compensate for thewearing action of the engagedends of said sections, including a nut threadedly engaged on saidtubular member and adapted to abut the rim of a wheel equipped with thetire, and means for fixedly holding said nut in adjusted positions.

ARTHIIB C'. SIWITH.

